crypto: vmx - Adding CBC routines for VMX module

/**

 * AES CBC routines supporting VMX instructions on the Power 8

 *

 * Copyright (C) 2015 International Business Machines Inc.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; version 2 only.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 *

 * Author: Marcelo Henrique Cerri <mhcerri@br.ibm.com>

 */

#include <linux/types.h>

#include <linux/err.h>

#include <linux/crypto.h>

#include <linux/delay.h>

#include <linux/hardirq.h>

#include <asm/switch_to.h>

#include <crypto/aes.h>

#include <crypto/scatterwalk.h>

#include "aesp8-ppc.h"

struct p8_aes_cbc_ctx {

    struct crypto_blkcipher *fallback;

    struct aes_key enc_key;

    struct aes_key dec_key;

};

static int p8_aes_cbc_init(struct crypto_tfm *tfm)

{

    const char *alg;

    struct crypto_blkcipher *fallback;

    struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);

    if (!(alg = crypto_tfm_alg_name(tfm))) {

        printk(KERN_ERR "Failed to get algorithm name.\n");

        return -ENOENT;

    }

    fallback = crypto_alloc_blkcipher(alg, 0 ,CRYPTO_ALG_NEED_FALLBACK);

    if (IS_ERR(fallback)) {

        printk(KERN_ERR "Failed to allocate transformation for '%s': %ld\n",

                alg, PTR_ERR(fallback));

        return PTR_ERR(fallback);

    }

    printk(KERN_INFO "Using '%s' as fallback implementation.\n",

            crypto_tfm_alg_driver_name((struct crypto_tfm *) fallback));

    crypto_blkcipher_set_flags(fallback,

            crypto_blkcipher_get_flags((struct crypto_blkcipher *) tfm));

    ctx->fallback = fallback;

    return 0;

}

static void p8_aes_cbc_exit(struct crypto_tfm *tfm)

{

    struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);

    if (ctx->fallback) {

        crypto_free_blkcipher(ctx->fallback);

        ctx->fallback = NULL;

    }

}

static int p8_aes_cbc_setkey(struct crypto_tfm *tfm, const u8 *key,

    unsigned int keylen)

{

    int ret;

    struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);

    pagefault_disable();

    enable_kernel_altivec();

    ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);

    ret += aes_p8_set_decrypt_key(key, keylen * 8, &ctx->dec_key);

    pagefault_enable();

    ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);

    return ret;

}

static int p8_aes_cbc_encrypt(struct blkcipher_desc *desc,

    struct scatterlist *dst, struct scatterlist *src,

    unsigned int nbytes)

{

    int ret;

    struct blkcipher_walk walk;

    struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(

            crypto_blkcipher_tfm(desc->tfm));

    struct blkcipher_desc fallback_desc = {

        .tfm = ctx->fallback,

        .info = desc->info,

        .flags = desc->flags

    };

    if (in_interrupt()) {

        ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src, nbytes);

    } else {

        pagefault_disable();

        enable_kernel_altivec();

	blkcipher_walk_init(&walk, dst, src, nbytes);

        ret = blkcipher_walk_virt(desc, &walk);

        while ((nbytes = walk.nbytes)) {

			aes_p8_cbc_encrypt(walk.src.virt.addr, walk.dst.virt.addr,

				nbytes & AES_BLOCK_MASK, &ctx->enc_key, walk.iv, 1);

			nbytes &= AES_BLOCK_SIZE - 1;

			ret = blkcipher_walk_done(desc, &walk, nbytes);

	}

        pagefault_enable();

    }

    return ret;

}

static int p8_aes_cbc_decrypt(struct blkcipher_desc *desc,

    struct scatterlist *dst, struct scatterlist *src,

    unsigned int nbytes)

{

    int ret;

    struct blkcipher_walk walk;

    struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(

            crypto_blkcipher_tfm(desc->tfm));

    struct blkcipher_desc fallback_desc = {

        .tfm = ctx->fallback,

        .info = desc->info,

        .flags = desc->flags

    };

    if (in_interrupt()) {

        ret = crypto_blkcipher_decrypt(&fallback_desc, dst, src, nbytes);

    } else {

        pagefault_disable();

        enable_kernel_altivec();

	blkcipher_walk_init(&walk, dst, src, nbytes);

        ret = blkcipher_walk_virt(desc, &walk);

        while ((nbytes = walk.nbytes)) {

			aes_p8_cbc_encrypt(walk.src.virt.addr, walk.dst.virt.addr,

				nbytes & AES_BLOCK_MASK, &ctx->dec_key, walk.iv, 0);

			nbytes &= AES_BLOCK_SIZE - 1;

			ret = blkcipher_walk_done(desc, &walk, nbytes);

		}

        pagefault_enable();

    }

    return ret;

}

struct crypto_alg p8_aes_cbc_alg = {

    .cra_name = "cbc(aes)",

    .cra_driver_name = "p8_aes_cbc",

    .cra_module = THIS_MODULE,

    .cra_priority = 1000,

    .cra_type = &crypto_blkcipher_type,

    .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,

    .cra_alignmask = 0,

    .cra_blocksize = AES_BLOCK_SIZE,

    .cra_ctxsize = sizeof(struct p8_aes_cbc_ctx),

    .cra_init = p8_aes_cbc_init,

    .cra_exit = p8_aes_cbc_exit,

    .cra_blkcipher = {

        .ivsize = 0,

        .min_keysize = AES_MIN_KEY_SIZE,

        .max_keysize = AES_MAX_KEY_SIZE,

        .setkey = p8_aes_cbc_setkey,

        .encrypt = p8_aes_cbc_encrypt,

        .decrypt = p8_aes_cbc_decrypt,

    },

};